arduino-nano: Add GPIO input/output/read/write support

include/arduino-nano/driver/gpio.h

 #ifndef GPIO_H
 #define GPIO_H
 
+#include <avr/io.h>
+
 class GPIO {
 	private:
 		GPIO(const GPIO &copy);
 
 	public:
 		GPIO () {}
+
+		enum Pin : unsigned char {
+			pb0 = 8,
+			pb1 = 9,
+			pb2 = 10,
+			pb3 = 11,
+			pb4 = 12,
+			pb5 = 13,
+			pb6 = 14,
+			pb7 = 15,
+			pc0 = 16,
+			pc1 = 17,
+			pc2 = 18,
+			pc3 = 19,
+			pc4 = 20,
+			pc5 = 21,
+			pc6 = 22,
+			pd0 = 24,
+			pd1 = 25,
+			pd2 = 26,
+			pd3 = 27,
+			pd4 = 28,
+			pd5 = 29,
+			pd6 = 30,
+			pd7 = 31
+		};
+
 		void setup();
 		void led_on(unsigned char id);
 		void led_off(unsigned char id);
 		void led_toggle(unsigned char id);
+		inline void input(unsigned char const pin) {
+			if (pin < 8) {
+			} else if (pin < 16) {
+				DDRB &= ~_BV(pin - 8);
+			} else if (pin < 24) {
+				DDRC &= ~_BV(pin - 16);
+			} else if (pin < 32) {
+				DDRD &= ~_BV(pin - 24);
+			}
+		}
+		inline void output(unsigned char const pin) {
+			if (pin < 8) {
+			} else if (pin < 16) {
+				DDRB |= _BV(pin - 8);
+			} else if (pin < 24) {
+				DDRC |= _BV(pin - 16);
+			} else if (pin < 32) {
+				DDRD |= _BV(pin - 24);
+			}
+		}
+		inline unsigned char read(unsigned char const pin) {
+			if (pin < 8) {
+			}
+			if (pin < 16) {
+				return (PINB & _BV(pin - 8));
+			}
+			if (pin < 24) {
+				return (PINC & _BV(pin - 16));
+			}
+			if (pin < 32) {
+				return (PIND & _BV(pin - 24));
+			}
+			return 0;
+		}
+		inline void write(unsigned char const pin, unsigned char value) {
+			if (pin < 8) {
+			} else if (pin < 16) {
+				if (value) {
+					PORTB |= _BV(pin - 8);
+				} else {
+					PORTB &= ~_BV(pin - 8);
+				}
+			} else if (pin < 24) {
+				if (value) {
+					PORTB |= _BV(pin - 16);
+				} else {
+					PORTB &= ~_BV(pin - 16);
+				}
+			} else if (pin < 32) {
+				if (value) {
+					PORTB |= _BV(pin - 24);
+				} else {
+					PORTB &= ~_BV(pin - 24);
+				}
+			}
+		}
 };
 
 extern GPIO gpio;

src/arch/arduino-nano/Makefile.inc

@@ -26,6 +26,7 @@ OBJECTS = ${TARGETS:.cc=.o}
 
 build/system.elf: ${OBJECTS}
 	${CXX} ${COMMON_FLAGS} ${CXXFLAGS} -Wl,--gc-sections -o $@ ${OBJECTS}
+	avr-size --format=avr --mcu=${MCU} $@
 
 build/system.hex: build/system.elf
 	${OBJCOPY} -O ihex ${@:.hex=.elf} $@